The hepatic uptake and net hepatic clearance of conjugated bilirubin in rats is substantially faster than that of the unconjugated bilirubin. An appreciable affinity of conjugated bilirubin for intrahepatic binding proteins, such as ligandin, has been demonstrated. The existence of a significant intrahepatic storage pool for bilirubin monoglucuronide, but not bilirubin diglucuronide, has also been established. These observation may imply that the formation and excretion of bilirubin diglucuronide occurs directly from the canalicular pool of the hepatocyte. Saturable binding of sulfobromophthalein (BSP) to hepatic canalicular and plasma membranes has been demonstrated. Furthermore, proteins with affinities for bilirubin and BSP have been isolated from hepatic cell surface membrane fractions. In studies of bile salt transport it has been shown that microfilaments may be important hepatic active transport systems and that the bile salt independent fraction of bile may be dependent on the excretion of currently unidentified anions which are not bile salts.